Proceedings of the World Congress on Engineering 2012 Vol III
WCE 2012, July 4 - 6, 2012, London, U.K.
Design and Construction of an Orange Juice
Extractor
Sylvester A. Aye*, and Abugh Ashwe, *Member, IAENG

Abstract—It is required to construct a manually operated
household orange juice extractor to be portable and used in
extraction of juice. It is also required to be cheap and easily
manufactured. It can be easily operated and its efficiency is
very high. The dimensions are 160mm diameter and 350mm
height. The machine combines the actions of chopping and
beating, often by macerating. It consists of two main parts – a
goblet and a manually operated mechanical unit. The manually
operated mechanical unit consists of a pair of bevel gears, two
bearings and two shafts. The bevel gear casing was constructed
using 2mm thickness of mild steel sheet. The bearings were
then put into position. Afterwards, the shafts were fastened to
the bevel gear and passed through the bearings. The handle
was then welded to the horizontal shaft. Similarly, the goblet
was formed using 1mm thickness of mild steel sheet. Small
sharpened blades were then made and fixed onto the impeller
shaft. A bearing was then fixed underneath and a shaft passed
through. A dynamic seal was put between the shaft, bearings
and goblet to prevent leakage. The connection between the
gear casing and goblet was done by means of an Oldham
coupling designed for misalignment. The machine can extract
the juice of about 180-220 oranges per hour.
Index Terms—juice extractor, gears, bearings, shaft, orange
O
I. INTRODUCTION
ne of the oldest cultivated fruits, oranges are among
the most popular of fruits for eating out of hand and are
by far the most important source of fresh, frozen and canned
juice.
A. The orange
The orange fruit is a specialised type of berry known to
botanists as hesperidia. It has a soft, pithy central axis
surrounded by 10-15 segments containing pulp and juice.
Enclosing the segments is a leathery, oily rind that has a
white spongy inner part and a harder, orange coloured outer
part containing many glands that secrete oil. The segment
juice contains sugar; several organic acids (chiefly citric
acid) many other components; which give it a distinctive
flavour; and high amounts of vitamins A, B and C.
Manuscript received March 23, 2012; revised April 12, 2012. Sylvester
A. Aye is with the Department of Mechanical and Aeronautical Engineering
of the University of Pretoria, South Africa and on study leave from the
Department of Mechanical Engineering of the University of Agriculture,
Makurdi, Benue State, Nigeria. (Corresponding Author: Phone: +27 (0)
74 151
2328;
e-mail:
[email protected]
or
[email protected]).
Abugh Ashwe is with the Department of Mechanical Engineering
of
the University of Agriculture, Makurdi, Benue State, Nigeria. (e-mail:
[email protected]).
ISBN: 978-988-19252-2-0
ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online)
Oranges grow on evergreen trees of the family Rutaceae.
The trees grow to a height of about 30 feet (9m) and are
symmetrical and upright. The fruit varies in the number of
seeds, from none to many.1,2
B. Objectives
The aim of this project is to design and construct a manually
operated juice extractor that will extract juice from the
orange fruit using available local materials.
C. Importance of the project
Prior to 1920, the orange was considered principally as a
dessert fruit. With the spread of orange juice drinking,
instead of eating the flesh of the fruit and the growing
appreciation of the nutritional value of oranges which are
rich in vitamins A, B and C, there is the need for the design
and construction of machines for the extraction of juice so
they could be stored in refrigerator or canned and drunk at
any time.
II. DESIGN CALCULATION
A. Introduction
Design can be described as a decision-making process
where plans are formulated for the physical development of
a machine or piece of equipment, whereby all the user’s
requirements are satisfied.
B. Definition of the problem
It is required to design an extractor to obtain juice from
oranges with little effort.
The machine should be
i. Easily operated.
ii. Cheaply and easily manufactured with local resources.
iii. Easily maintained
iv. Portable and easily stored.
C. The components, their function and the operation of the
machine
The components of the orange juice extractor may be
broadly classified into the goblet and mechanically operated
unit. The goblet consists of the following components: a
bearing, a bearing support, impeller shaft, a dynamic seal,
small sharp blades attached to the impeller. However, the
mechanically operated unit consists of two bearings, two
bearing supports, a pair of level gears, two pinions, a gear
shaft and a handle. The bearings allow for free rotation of
the shafts. The bearing supports hold the bearings in
position and the dynamic seal prevents leakage of the juice.
WCE 2012
Proceedings of the World Congress on Engineering 2012 Vol III
WCE 2012, July 4 - 6, 2012, London, U.K.
The operator turns the handle and the motion is transmitted
to the pinion through the pinion shaft and then to the gear
which transmits it to the gear shaft and thence to the
impeller shaft. Motion is transmitted from the mechanical
unit to the goblet in impeller shaft by means of an Oldham
coupling. The blades at the top of the impeller shaft rotate in
the orange which has been cut and placed on it, thereby
extracting juice from it. Sectional views of the assembly and
the various components are shown in figures 1 and 2 of the
appendix respectively.
D. Material selection
The material for the pinion is to be of medium carbon steel
with 0.45% carbon, hardness with high tempering and of
BHN194 and allowable stress (  ) = 500N/mm2;
(  -1)b = 130N/mm2. For the gear, medium carbon steel is
also chosen with up to 0.45% carbon, but normalised and of
BHN 173 and allowable stress and of (  ) = 450N/mm2 and
(  -1)b = 116N/mm2.
E. Computation of parameters of the bevel gear
Transmission ratio is the ratio of speed of pinion to the
speed of the gear, given by equation 1.
i = N1/N2
(1)
where N1 is speed of the pinion and N2 is the speed of the
gear. N1 = 100rpm, N2 = 300rpm, hence, i = 300/100 = 3:1
Power, P, of a manually operated system is 1/7th of horse
power, i.e. approximately 107W. The torque of the machine
is given by the ratio of power to angular speed, w, as shown
in equation 2.
T = P/w
(2)
The angular speed is given by equation 3, where N is the
number of revolutions per minute.
(3)
w = 2  N/60
Substituting equation 3 in equation 2, we obtain torque as
given in equation 4
(4)
T = p.60/(2  N)
Substituting the value of power of 107W and rotational
speed of 100rpm for the pinion in equation 4, the torque
value, T, is 10.2Nm
From this the tooth length factor is chosen to be ψRe = 0.30
from charts.
From chart and for M2 = T = 10.2 x 103 Nmm, ψRe = 0.3,
i = 3:1, (  e)cs = 450N/mm and K = 1.6, we see that
external pitch diameter, de2 = 100mm.
The number of teeth for pinion Z1, say 20 (any number for
which undercutting will not result Z1>18) is suitable. Hence,
the number of teeth of gear (Z2) is given by equation 5 as
60, since i = 3.
(5)
Z2 = Z1i
External pitch module, Me, is given by equation 6 below.
For external pitch diameter of 100mm and Z2 of 60, the
ISBN: 978-988-19252-2-0
ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online)
value of Me is 1.67mm. From tables, the next standard
module is chosen as 2.0mm.
(6)
Me = de2/Z2
Refining the basic reducer parameters, namely external
pitch diameter, de2 is given by equation 7. Substituting Me
and Z2 in equation 7, we obtain de2 as 120mm.
(7)
de2 = MeZ2
In our case, de2 = 125 and i = 3.15 are standard as seen in
the relevant tables 8 and 9. Also, Me = 2 has been
standardised.
To verify the speed, n2 for i = 3.15. For i = 3.15, Actual rpm
n2 = n1/i = 300/3.15 = 95.239; n2 is taken to be 98. Deviation
from given rpm is (100-98)/100 x 100% = 2% which is
allowable.
(8)
n2 = n1/i
Pitch cone radius, Re, is given by equation 9 below. For Me,
Z1 and Z2 values of 2mm, 60 and 20 respectively, Re value
is obtained as 63.25mm.
(9)
Re = Me/2(Z12 + Z22 )
The tooth length or width of face, b, is given by equation
10. For values of ψRe and Re of 0.3 and 63.25mm
respectively, b is obtained as 18.975mm. From tables and
standards b is selected as 19mm.
(10)
b = ψRe x Re
External pitch diameter of pinion is given by equation 11.
For Me and Z1 values of 2 and 20 respectively, del is
obtained as 40mm.
(11)
del = MeZ1
Pitch angle cot  1 = 3.15; from which
obtained from equation 12 below.
 2 = (900 -  1)

1
= 72.390 is
(12)
Mean pitch diameter, d1, is given by equation 13 and the
value is obtained as 102.46mm.
(13)
d1 = 2(Re-0.5b) Sin  1
Mean pitch module, M, is given by equation 14 and the
value obtained as 5.12mm.
(14)
M = d1/ Z1
Mean pitch line velocity, V, is given by equation 15 below
and the value obtained as 1.61m/s. From tables, at this speed
for straight bevel forth gearing and for hardness <BHN 350,
9th degree of accuracy can be taken but because of the need
to lower the dynamic load, instead, of 9th, the 8th was
adopted.
(15)
V =  d1n1/60
Refinement of load factor is given by equation 16 and is
obtained as approximately 0.19 and for 8th degree of
accuracy.
(16)
ψd = b/d1
In the case that the pinion is mounted symmetrically at the
end of the shaft, K’ conc. = 1.15.
WCE 2012
Proceedings of the World Congress on Engineering 2012 Vol III
WCE 2012, July 4 - 6, 2012, London, U.K.
K conc. Is given by equation 17 and the value obtained is
1.0775.
K conc. = (K’ conc. + 1)/2
(17)
From tables, for V = 1.61m/s; BHN<350; 8th degree of
accuracy and for bevel gearing; Kdyn = 1.3.
Hence, Load factor, K, is given by equation 18 and the
value is approximately 1.4.
K = K conc. x Kdyn
(18)
The design contract stress is given by equation 19 below.
The value of K1 is 1.0 and the  cs is computed as
94.6N/mm2 Since 94.6 N/mm2 is less than the allowable
stress of 450 N/mm2 of the weaker component (the gear);
the design is safe
(19)
 cs = 1050/((1-0.5) ψRe)1(M2K.i)/(de32ψK1)]
≤(  )cs
Determination of main parameters or proportion of the
pinion and gear. Already we have de1 = 40mm;
de2 = 100mm and b = 19mm.
Tooth outside parameters, da1 and da2, are computed as
41.21mm and 103.81mm and are given by equations 20 and
21 respectively.
(20)
da1 = de1 + 2Me cos  1
da2 = de2 + 2Me cos


2
(23)
In checking the strength of teeth in Bending, Virtual number
of teeth of pinion, Zv or, is given by equation 24 and has the
value of approximately 66. Similarly, for the gear, Zv, is
given by equation 25 and has the value of approximately 63.
(24)
Zmod1 = Z1/cos  1
Zmod2 = Zv = Z2/cos

G. Determination of shaft size on the basis of strength
The maximum shear stress,  max , of the shaft is given by
equation 28 below.
 max  16 /( d 3 ) (( K m M )  ( K t T ))
where
 max
(28)
is the maximum shear stress, d is the shaft
diameter, Km is the numerical combined shock and fatigue
factor to be applied, Kt is the corresponding factor to be
applied to the computed torques, M is the bending moment,
T is torque. For this case bending moment is negligible. Kt
is equal to 1.0 for rotating shaft with gradually applied
loads. Assuming bending moment is negligible equation 29
is obtained from equation 28 by making shaft diameter the
subject of the formula. For  max = 30N/mm2, T = 10.2Nm,
the shaft diameter is obtained as approximately 12mm.
(29)
d = (16/(   max )T3/2)
(21)
2
Tooth root diameters, de1 and de2, are computed as 38.9mm
and 95.23mm and are given by equations 22 and 23
respectively.
(22)
de1 = de1 – 2.5Me cos  1
de2 = de2 – 2.5Me cos
F. Shaft design
A shaft is a rotating member, usually of circular cross
section (either solid or hollow), transmitting power. It is
supported by bearings and support gears, sprockets, wheels,
rotors, etc. and is subjected to torsion and to transverse or
axial loads, acting singly or in combination.
2
(25)
From tables, the tooth from factory, for virtual numbers of
teeth Ze or Zv = 66 is y ≈ 0.471. Similarly, for Ze = 63,
y = 0.470.
Comparative weighting of bending strength of pinion and
gear teeth is given by equation 26. For the pinion and gear
the values obtained are 61.23N/mm2 and 54.52N/mm2
respectively.
(26)
y(  )b = y x (  -1)b
Design bending stress,  b , at the weakest section of the
pinion tooth is given by equation 27 below. For KL = 1,
 b = 14.1N/mm which is less than (  b-1)b1 = 130N/mm
and thus safe.3,4,5,6,7,8,9,10,11,12
 b = (2.35 M1K Cos ψ )/ (Z1 y1 b m2 KL);
ISBN: 978-988-19252-2-0
ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online)
H. Bearing selection
Equations for calculating basic static load rating(Co) in Kg
for radial ball bearings is given by equation 30.
(30)
Co = fo I Z D2 cos 
where i is number of balls in the bearing, Z is the number of
balls per row, D is the ball diameter in mm,  is the normal
angle between the line of action of the ball load and a plane
perpendicular to the bearing axis, fo is 0.34 for self-aligning
ball bearing made of hardened steel.
Static equivalent load (Po) is calculated using equation 31
below.
Po = XoFr + YoFa
(31)
where Fr is radial load and Fa is the thrust load, Xo is radial
factor; Xo = 0.6 for radial contact groove ball bearing, Yo is
thrust factor; Yo = 0.5 for radial contact groove ball
bearing.
For shaft connected by gears with rotating machines, and no
impact, load factor, k, takes any value between 1.1 – 1.5.
Desired Life is given by equation 32.
L = (C/P)k
(32)
Where C is basic dynamic load rating, P is equivalent load
K = 3 for ball bearings and 10/3 for roller bearings.
From tables for machines used for short periods or
intermittently, i.e. manually operated machines, and whose
breakdown would not have serious consequences, generally,
Life in working hours, Lh = 4000 – 8000.
(27)
WCE 2012
Proceedings of the World Congress on Engineering 2012 Vol III
WCE 2012, July 4 - 6, 2012, London, U.K.
For a ball bearing with life of 4000 hours at 100rpm, from
tables C/P = 2.88. For C/P = 2.8, for ball bearings, life in
millions of revolution is 23.
Also, for a bearing with life of 4000 hours at 300rpm from
tables C/P = 4.01. For C/P = 4.01 for ball bearings life in
millions of revolution is 65.
For d = 12mm, D = 28mm, H = 11mm, d2min = 10.2mm,
r≈1mm; static capacity, Co = 15000kg; Dynamic capacity,
C = 10.40kg; Maximum permissible speed = 8000rpm.
I. Couplings
A coupling is a device which connects two parts of a
mechanical system. An Oldham coupling (double slider
coupling) is used for shafts with lateral misalignment
amounting to as much as 5% of the shaft diameter with
considerable axial play and with relatively small angular
misalignment (one degree). It consists of three parts – two
slotted hubs and a central piece having two tongues, one on
each face, perpendicular to each other.
The design is based on allowable pressure, P on the sliding
surface, given as P = 67kg/cm2 from tables.
The force, F due to the total pressure on each side of the
tongue is given by equation 33.
F = PDh/4
(33)
where D is the outer diameter of the centre piece ≈ 3 to 4 x
shaft diameter, h is the height of tongue, and torque
transmitted by both sides of the tongue is given by equation
34.
T = 2F x D/3
(34)
Substituting equation 33 in equation 34, we obtain equation
27 below.
T = 1/6 P D2 h
(35)
For this machine, from tables, allowable torque, T, is
10.24Nm.
2
Allowable pressure of sliding surfaces P = 67Kg/cm
Shaft diameter, ds = 12mm
Outside diameter of centre piece is given by equation 35.
Substituting 12mm for ds in equation 36 we obtain D as
48mm.
D ≈ 4 x ds
(36)
Width of tongue W is given by equation 37 and has a value
of 5.4mm. Hence, the value is approximated to 6mm.
W = 0.45 x ds
(37)
Hence, from equation 33, making height of tongue, h, the
subject of the formula we obtain equation 38 and the value
of h as 3.96mm. This is approximated to 4mm.
h = 6T/(PD2)
(38)
ISBN: 978-988-19252-2-0
ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online)
J. Seals
Seals are employed to reduce leaks through the gaps
between the moving and stationery parts and also to prevent
the flow of a substance between two machines having
relative motion.
Dynamic shaft seals are relatively more insensitive to
dimensional variations and are used for high speed and
continuous duty. These seals have positive sealing ability
and have low initial cost. The life is dependent on the shaft
condition and its finish, speed, alignment, end play,
eccentricity, etc., temperature at seal, fluid pressure on seal,
and nature of sealed medium.
The life of the seal can be increased by proper and
continuous lubrication of the seal, using a shaft with good
surface finish, having a minimum disturbance of seal due to
shaft end play or eccentricity, keeping dirt away from shaft
and seal interface, etc.
The material for the sealing elements could be:
Nitrile with excellent abrasion resistance and temperature
range of 0-75oC; Polyactic with fair abrasion resistance and
temperature range of 0-100oC; Leather with excellent
resistance and temperature range of -10-95oC; and Silicon
with good resistance and temperature range of -25-260oC;
III. ASSEMBLY, MAINTENANCE AND COST ANALYSIS
A. Assembly
The machine is assembled as shown in the assembly
drawing (see drawing attached). The bevel gear casing is
made of 2.0mm thickness of mild steel which is joined
together by welding. The machine is so constructed that it
still remains steady on the ground while in operation. In the
assembly of the lower member the bearings are put in
position after which the bevel gears mounted on shafts are
put in position. For the goblet, the bearing and mechanical
seal are put in position. The impeller shaft is then passed
through.
B. Maintenance
The design is simple, so that the maintenance of the
machine can be done with ease. The goblet should always
be washed and dried after use. Any repair work on the
impeller can be done with ease of access to the impeller.
The goblet can easily be removed from the lower member.
The goblet should also be periodically checked for leakage.
Bearings should be lubricated periodically or whenever
there is no grease in them. Easy access to the bearings is
provided. Equally, the bevel gear should also be lubricated
whenever dry to ensure longevity.
C. Cost analysis
Cost evaluation depends on the current market price and
cost of labour. Market prices are never uniform and tend to
rise sharply and unpredictably. Labour costs also vary
considerably. This depends on the workshop size, efficiency
and reliability of the personnel needed to perform some of
the work. Based on the above, a correct analysis is difficult.
Cost evaluation for commercial production involves
WCE 2012
Proceedings of the World Congress on Engineering 2012 Vol III
WCE 2012, July 4 - 6, 2012, London, U.K.
consideration of protracted economic principles and
characteristics such as direct cost, indirect cost, overhead
cost and so on. This was done by estimating production of a
single component which gives an insight into commercial
production. The table below shows approximate labour and
material costs for production of a manually operated
household orange juice extractor.
ITEM
TABLE I
MATERIAL COST
UNIT
COST(N)
QTY
Bevel gear(pair)
Bearings
Handle (Rubber or plastic)
Gear shaft
Pinion shaft
Impeller shaft
1mm sheet of metal for gobet
2mm sheet of metal for base
(lower base)
Dynamic seal
Impeller blades
Engaging union
Sieve
Bevel gear (pair)
2
3
1
1
1
1
1
1
500.00
200.00
250.00
200.00
200.00
200.00
500.00
800.00
1
1
1
1
2
200.00
200.00
250.00
100.00
500.00
TOTAL
COST
(N)
($)
1000.00 6.45
600.00 3.87
250.00 1.61
200.00 1.29
200.00 1.29
200.00 1.29
500.00 3.23
800.00
5.16
200.00 1.29
200.00 1.29
250.00 1.61
100.00 0.65
1000.00
6.45
.
D. Labour cost
Cutting, bonding, machining, welding
Fitting, painting
N500.00
N5,000.00
E. Total
The total cost for the production approximates to
N5,000.00 as computed from table 1 for material cost and
the labour cost. The total cost per item for large-scale
production would be less than this amount stated above.
F. Cost of labour
It is the expected that a technician would collect as pay
during the period of fabrication excluding the costs of
materials, the sum of N1,000.00 per day. An estimated five
working day period would be required, and this translates to
N5,000.00.
G. Overhead costs
This includes all other costs that may not be wholly
accounted for, e.g. power used in machine operations, tax
for production and marketing the juice extractor,
transportation, etc. Other costs, which include welding, risk
allowance, depreciation, etc., are estimated at N500.00 per
unit for the juice extractor.
Summary of Total cost = (5,000 + 500) = N5,500.00
Approximately N5,500.00 ≈ $36.67 is required to fabricate
this machine.
IV. CONCLUSION AND RECOMMENDATIONS
A. Conclusion
The orange juice extractor has been designed and
constructed using scientific and engineering principles. The
machine has a diameter of 160mmm and a height of
350mm. The juice extraction is achieved by means of small
sharpened blades on a shaft which rotates with the aid of the
bevel drive. The rotation is achieved by turning the handle.
The project has made it possible to extract juice from orange
fruits easily and faster. The machine is of a unique type and
is readily available to those that are interested at an
affordable price.
Figure 1: Sectional view of the assembly
ISBN: 978-988-19252-2-0
ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online)
WCE 2012
Proceedings of the World Congress on Engineering 2012 Vol III
WCE 2012, July 4 - 6, 2012, London, U.K.
Figure 2: Component parts
APPENDIX
Dessert (n) - Sweet course served at the end of meal.
Goblet (n) - Hopper where oranges are fed
Juice (n) - Liquid part of vegetables, fruit or meat.
Rind (n) - Outer coating of fruits, cheese or bacon
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Higgins & Morrow, Maintenance and Engineer’s Handbook.
Perry & Chilton, Chemical Engineer’s Handbook.
Tyler G. Hicks, Standard Handbook of Engineering Calculations.
Ijohah K. Monica, Design and construction of a manually operated
corking machine for small scale fruit drink business, Makurdi.
[8] Igu Akachukwu et al., Practical gear design (unpublished).
[9] Peter Fellow & Ann Hampton, Small scale food processing – A guide
to appropriate equipment. London, 1992.
[10] Attah I Ogaba, Design and construction of 3 tons multipurpose screw
jack, Makurdi. 1995.
[11] Robert H. Perry & Cecil H. Chilton, Chemical Engineer’s
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[12] Tyongbea Emmanuel Ier, Design of a paint mixer, Makurdi, 1995.
ISBN: 978-988-19252-2-0
ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online)
WCE 2012